This invention relates generally to apparatus for driving rotatable rolls and, more particularly, to apparatus for driving a rotatable mantle which is mounted by bearings on a fixed axle, such as a mantle of a deflection compensated roll of a paper machine.
Apparatus for driving a rotatable mantle fitted by bearings on a fixed axle, such as the mantle of a deflection-compensated roll of a paper machine, are known and generally include one or more drive gears mounted on respective axles which themselves are fitted by bearings into a carrier located in the region of the end of the fixed axle. Such drive gear or gears mesh with and drive a gear ring connected to the rotatable mantle.
Reference is made to Finnish Publication Print No. 56,434 which illustrates a drive mechanism of the type with which the present invention is concerned. Such drive mechanism utilizes a drive gear or gears which mesh with and drive an internally toothed gear ring mounted on the rotatable mantle. The drive apparatus disclosed in Finnish Publication Print No. 56,434 has as its principal novel feature that the gear carrier is installed within a shell fixedly connected with the rotatable mantle and supported by rollers or slide-contact devices and/or within the rotatable mantle so that the carrier is able to assume a position with the mantle as a fixed unit. The carrier is clutched so as to be fixed against rotation around the fixed axle by suitable devices which allow the carrier to assume positions along with the mantle as described above.
The apparatus disclosed in Finnish Publication Print No. 56,434 has been found to have certain drawbacks. One such drawback is that the apparatus necessitates the use of special bearings having quite large diameters and whose rolling surfaces are expensive and difficult to manufacture due to the extensive machining, tempering and grinding operations. Standard bearings having integral outer and inner races cannot be utilized in the disclosed apparatus. A second drawback of the known apparatus is that it is necessary in the construction of the apparatus to machine the fixed center axle of the roll or mantle in order to provide spaces for the drive gear or gears. This creates problems particularly when low drive ratios are required as the diameter of the gears therefore become large thereby making it necessary to machine the center axle to a larger extent with consequent loss of strength of the axle.
Another problem which is not solved by the apparatus disclosed in Finnish Publication Print No. 56,434 is in the sealing of the gear box constituting the gear carrier. Thus, in the apparatus disclosed therein, it is necessary to seal a ring-shaped axle opening at the outer end of the gear box with respect to the outside surface. Still another drawback of the known drive apparatus is that the outer diameter of the gear drive is the same in all directions and that due to the particular construction it is difficult to reduce the size of this diameter to less than the diameter of the roll which is desirable from the point of view to facilitate mating of the drive gears with the particular roll.
Reference is also made to U.S. Pat. No. 3,889,334 which illustrates a drive mechanism for a rotatable mantle fitted with bearings on a fixed axle of the type having a feature wherein the gear box is fixedly attached to a stand on which an end of the fixed axle of the rotatable mantle is supported. However, this drive apparatus is not entirely satisfactory in that the same requires the use of floating gears which tend to cause noise and vibrations. Another problem in the apparatus disclosed in this U.S. patent is in making the seal between the end portion of the deflecting roll and the gear box a tight and secure one.